I agree with Carol, this does not sound like an overpayment but more likely a posting or a rounding issue. Overpayments occur, for example, when a service is paid that should have been denied, or when a reduction that should have been applied was not applied correctly. Discrepancies of a penny or two can appear when there is a difference in rounding numbers on calculations, such as for interest, multiple procedure reductions, or patient share portions which result in a fraction of a cent. Your Medicare statement should balance exactly if you go through it carefully, but even if it is really off by a penny or two, I don't know of any practice that would refund this or of any payer that would expect this to be refunded - the cost or processing a such refund would far exceed the amount of the overpayment. If you are really that concerned about it though, create a small balance credit adjustment code in your system to adjust these off and then you can track them. If the credits accumulate over time and become significant amount, and deal with them at that time.